Urban growth, heat islands, humidity, climate change: the costs multiply in tropical cities



During a heatwave in late 2018, Cairns temperatures topped 35°C nine days in a row and sensors at some points in the CBD recorded 45°C.

Taha Chaiechi, James Cook University and Silvia Tavares, James Cook University

Some 60% of the planet’s expected urban area by 2030 is yet to be built. This forecast highlights how rapidly the world’s people are becoming urban. Cities now occupy about 2% of the world’s land area, but are home to about 55% of the world’s people and generate more than 70% of global GDP, plus the associated greenhouse gas emissions.

So what does this mean for people who live in the tropical zones, where 40% of the world’s population lives? On current trends, this figure will rise to 50% by 2050. With tropical economies growing some 20% faster than the rest of the world, the result is a swift expansion of tropical cities.

Population and number of cities of the world, by size class, 1990, 2018 and 2030.
World Urbanization Prospects 2018, United Nations DESA Population Division, CC BY



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The populations of these growing tropical cities already experience high temperatures made worse by high humidity. This means they are highly vulnerable to extreme heat events as a result of climate change.

For example, extremely hot weather overwhelmed Cairns last summer. By December 3 2018, the city had recorded temperatures above 35°C nine days in a row. Four consecutive days were above 40°C.

Cairns’ heatwave summer.
Authors, using BOM temperature data

For our research, temperature and humidity sensors were strategically placed in the Cairns CBD to represent people’s experience of weather at street level. These recorded temperatures consistently higher than the Bureau of Meteorology (BoM) recordings, reaching 45°C at some points.

Highest temperatures recorded by James Cook University weather data sensors during the November-December 2018 heatwave in Cairns.
Image: Bronson Philippa, Author provided

Local effects magnify heatwave impacts

Urban environments in general are hotter than non-urbanised surroundings that are covered by vegetation. The trapping of heat in cities, known as the urban heat island effect, has impacts on human health, animal life, social events, tourism, water availability and business performance.

The urban heat island effect intensifies the impacts of increasing heatwaves on cities as a result of climate change.

Projections of increased heatwave frequency for Cairns region using visualisation platform on Queensland Future Climate Dashboard.
Queensland Future Climate Dashboard/Queensland Government, CC BY

But it is important to remember that other local factors also influence these impacts. These include the scale, shape, materials, composition and growth of the built environment in a particular location and its surrounding areas.

The differences between the BoM data recorded at Cairns airport and the inner-city recordings show the impacts of urban expansion patterns, built form and choice of materials in tropical cities.

The linear layout of Cairns has, on one hand, enabled the formation of attractive places for commercial activities. As these activity centres evolve into focal points of urban life, they in turn influence all sorts of socioeconomic parameters.

On the other hand, the form the built environment takes changes the patterns of wind, sun and shade. These changes alter the urban microclimate by trapping heat and slowing or channelling air movements.

The layout and structures of Cairns CBD alter local microclimates by trapping heat and altering air flows.
State of Queensland 2019, CC BY



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Shifting the focus to the tropics

To date, a large body of research has explored the undesired consequences of climate change and urban heat islands. However, the focus has been on capital and metropolitan cities with humid continental climates. Not many studies have looked at the economic and social impacts in the tropical context, where hot and humid conditions create extra heat stress.

Add the combined effects of climate change and urban heat islands and what are the socio-economic consequences of heatwaves in a tropical city like Cairns? We see that climate change adds another dimension to the relationship between cities, economic growth and development.

This presents a huge opportunity to start thinking about building cities that are not superficially greenwashed, but which instead tackle pressing issues such as climate variability and create sustainable business and social destinations.




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In cold climates, heatwaves and urban heat islands are not necessarily undesired, but their negative impacts are more obvious and harmful in warmer climates. And these harmful impacts of heatwaves on our economy, environment and society are on the rise.

We have scientific evidence of the increasing length, frequency and intensity of heatwaves. The number of record hot days in Australia has doubled in the past five decades.

Projections of changes in heatwave frequency for northern Queensland in 2030 and 2070.
Queensland Future Climate Dashboard/Queensland Government, CC BY

What are the costs of heatwaves?

Increased exposure to heatwaves amplifies the adverse economic impacts on industries that are reliant on the health of their outdoor workers. This is in addition to the extreme heat-related fatalities and health-care costs of heatwave-related medical emergencies. As a PwC report to the Commonwealth on extreme heat events stated:

Heatwaves kill more Australians than any other natural disaster. They have received far less public attention than cyclones, floods or bushfires — they are private, silent deaths, which only hit the media when morgues reach capacity or infrastructure fails.

Heat also has direct impacts on economic production. A 2010 study found a 1°C increase resulted in a 2.4% reduction in non-agricultural production and a 0.1% reduction in agricultural production in 28 Caribbean-basin countries. Another study in 2012 found an 8% weekly loss of production when the temperature exceeded 32°C for six days in a row.

The 2017 Farm performance and climate report by the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) states:

The recent changes in climate have had a significant negative effect on the productivity of Australian cropping farms, particularly in southwestern Australia and southeastern Australia.

Average climate effect on productivity of cropping farms in southwestern and southeastern Australia since 2000–01 (relative to average conditions from 1914–15 to 2014–15).
Farm performance and climate, ABARES, CC BY

It’s not just farming that is vulnerable. A Victorian government report report this year estimated an extreme heatwave event costs the state’s construction sector A$103 million. The impact of heatwaves on the city of Melbourne’s economy is estimated at A$52.9 million a year on average.

Impacts of heatwaves on Victoria’s main economic sectors.
State of Victoria Department of Environment, Land, Water and Planning, CC BY

According to this report, economic costs increase exponentially as the severity of heatwaves increases. This has obvious implications for cities in tropical regions.

As the next step in our research, we are examining the relationship between local urban features, urban heat islands, the resulting city temperatures and their direct and indirect (spillover) effects on local and regional economic activities.




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The Conversation


Taha Chaiechi, Senior Lecturer, James Cook University and Silvia Tavares, Lecturer in Urban Design, James Cook University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Environment laws have failed to tackle the extinction emergency. Here’s the proof



Koalas are among the threatened native species worst affected by habitat loss.
Taronga Zoo

Michelle Ward, The University of Queensland; April Reside, The University of Queensland; Hugh Possingham, The University of Queensland; James Watson, The University of Queensland; Jeremy Simmonds, The University of Queensland; Jonathan Rhodes, The University of Queensland, and Martin Taylor, The University of Queensland

Threatened species habitat larger than the size of Tasmania has been destroyed since Australia’s environment laws were enacted, and 93% of this habitat loss was not referred to the federal government for scrutiny, our new research shows.

The research, published today in Conservation Science and Practice, shows that 7.7 million hectares of threatened species habitat has been destroyed in the 20 years since the Environment Protection and Biodiversity Conservation (EPBC) Act 1999 came into force.

The Southern black throated finch, one of the threatened native animals worst affected by habitat loss.
Eric Vanderduys/BirdLife Australia



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Some 85% of land-based threatened species experienced habitat loss. The iconic koala was among the worst affected. More than 90% of habitat loss was not referred or submitted for assessment, despite a requirement to do so under Commonwealth environment laws.

Our research indicates the legislation has comprehensively failed to safeguard Australia’s globally significant natural values, and must urgently be reformed and enforced.

What are the laws supposed to do?

The EPBC Act was enacted in 1999 to protect the diversity of Australia’s unique, and increasingly threatened, flora and fauna. It was considered a giant step forward for biodiversity conservation and was expected to become an important legacy of the Howard Coalition government.

A dead koala outside Ipswich, Queensland. Environmentalists attributed the death to land clearing.
Jim Dodrill/The Wilderness Society



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The law aims to conserve so-called “protected matters” such as threatened species, migratory species, and threatened ecosystems.

Clearing and land use change is regarded by ecologists as the primary threat to Australia’s biodiversity. In Queensland, land clearing to create pasture is the greatest pressure on threatened flora and fauna.

Any action which could have a significant impact on protected matters, including habitat destruction through land clearing, must be referred to the federal government for assessment.

Loss of potential habitat for threatened species and migratory species, and threatened ecological communities. Dark blue represents habitat loss that has been assessed (or loss that occurred with a referral under the EPBC Act) and dark red represents habitat loss that has not been assessed (or loss that occurred without a referral under The Act). Three panels highlight the southern Western Australia coast (left), Tasmania (middle), and northern Queensland coast (right).
Adapted from Ward et al. 2019

The law is not being followed

We examined federal government forest and woodland maps derived from satellite imagery. The analysis showed that 7.7 million hectares of threatened species habitat has been cleared or destroyed since the legislation was enacted.

Of this area, 93% was not referred to the federal government and so was neither assessed nor approved.

Bulldozer clearing trees at Queensland’s Olive Vale Station in 2015.
ABC News, 2017

It is unclear why people or companies are not referring habitat destruction on such a large scale. People may be self-assessing their activities and concluding they will not have a significant impact.

Others may be seeking to avoid the expense of a referral, which costs A$6,577 for people or companies with a turnover of more than A$10 million a year.

The failure to refer may also indicate a lack of awareness of, or disregard for, the EPBC Act.

The biggest losers

Our research found that 1,390 (85%) of terrestrial threatened species experienced habitat loss within their range since the EPBC Act was introduced.

Among the top ten species to lose the most area were the red goshawk, the ghost bat, and the koala, losing 3 million, 2.9 million, and 1 million hectares, respectively.

In less than two decades, many other imperilled species have lost large chunks of their potential habitat. They include the Mount Cooper striped skink (25%), the Keighery’s macarthuria (23%) and the Southern black-throated finch (10%).

(a) The top 10 most severely impacted threatened species include those that have lost the highest proportion of their total habitat, and (b) species who have lost the most habitat, as mapped by the Federal Government.
Adapted from Ward et al. 2019

What’s working, what’s not

We found that almost all referrals to the federal government for habitat loss were made by urban developers, mining companies and commercial developers. A tiny 1.3% of referrals were made by agricultural developers – despite clear evidence that land clearing for pasture development is the primary driver of habitat destruction.

Alarmingly, even when companies or people did refer proposed actions, 99% were allowed to proceed (sometimes with conditions).

The high approval rates may be derived, in part, from inconsistent application of the “significance” test under the federal laws.

Hundreds of protesters gather in Sydney in 2016 to demand that New South Wales retain strong land clearing laws.
Dean Lewins/AAP

For example, in a successful prosecution in 2015, Powercor Australia and Vemco] were fined A$200,000 for failing to refer clearing of a tiny 0.5 hectares of a critically endangered ecosystem. In contrast, much larger tracts of habitat have been destroyed without referral or approval, and without any such enforcement action being taken.

Clearer criteria for determining whether an impact is significant would reduce inconsistency in decisions, and provide more certainty for stakeholders.

The laws must be enforced and reformed

If the habitat loss trend continues, two things are certain: more species will become threatened with extinction, and more species will become extinct.

The Act must, as a matter of urgency, be properly enforced to curtail the mass non-referral of actions that our analysis has revealed.

The left pie chart illustrates the breakdown of industries referring their actions by number of referrals; the right pie chart illustrates the breakdown of industries referring their actions by area (hectares). Both charts highlight the agricultural sector as a low-referring industry.
Adapted from Ward et al. 2019

If nothing else, this will help Australia meet its commitment under the Convention on Biological Diversity to prevent extinction of known threatened species and improve their conservation status by 2020.




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Mapping the critical habitat essential to the survival of every threatened species is also an important step. The Act should also be reformed to ensure critical habitat is identified and protected, as happens in the United States.

Australia is already a world leader in modern-day extinctions. Without a fundamental change in how environmental law is written, used, and enforced, the crisis will only get worse.The Conversation

Michelle Ward, PhD Student, The University of Queensland; April Reside, Researcher, Centre for Biodiversity and Conservation Science, The University of Queensland; Hugh Possingham, Professor, The University of Queensland; James Watson, Professor, The University of Queensland; Jeremy Simmonds, Postdoctoral Research Fellow in Conservation Science, The University of Queensland; Jonathan Rhodes, Associate Professor, The University of Queensland, and Martin Taylor, Adjunct senior lecturer, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Australia has met its renewable energy target. But don’t pop the champagne



Wind energy has played a major role in Australia’s fulfilment of the renewable energy target.
Olivier Hoslet/AAP

Dylan McConnell, University of Melbourne

A wind farm project in Tasmania this week helped Australia reach something of a milestone, nudging it over the line to reach its renewable energy target.

The Clean Energy Regulator announced it had approved capacity from the 148.5 megawatt Cattle Hill wind farm project, meaning the nation’s Large-scale Renewable Energy Target will be fulfilled.

Federal energy and emissions reduction minister Angus Taylor seized on the development, suggesting it showed the government’s record investment in renewable energy was world-leading.

Energy and Emissions Reduction Minister Angus Taylor said renewables investment would continue to grow.
AAP

Taylor has previously declared his government will not extend the target – the primary national mechanism supporting renewable energy. But this week he insisted “investment is not slowing down”.

This bold claim flies in the face of the evidence. Investment in new renewable energy capacity is slowing down.

Losing momentum: Australian renewables investment has cooled in 2019.
Bloomberg New Energy Finance

The latest data from Bloomberg New Energy Finance clearly shows a 21% drop in investment from the 2018 to 2019 financial years.

As Australia’s emissions reduction task becomes ever more urgent, the investment downturn begs the question: what happens next?

In fact, Australia cruised over the line

It is ironic that the Morrison government rushed to claim a win on the renewable energy target when many in the Coalition had claimed it would be difficult to meet, or wanted it scrapped altogether.

The policy involved tradeable certificates which created a financial incentive for new or expanded renewable energy power stations, such as wind and solar farms.

Under the target just met, 33 terrawatt-hours (TWh) of Australia’s electricity would be produced by new renewables by 2020, bringing the total share of renewable energy to about 23.5%.

Mount Majura Solar farm near Canberra.
AAP/Lucas Cochleae



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The target was established by the Rudd Labor governmentand overhauled by the Abbott Coalition government after it came to power. It commissioned a contentious review of the target, then in 2015 reduced it to 33TWh after protracted negotiations with Labor.

As it transpired, that target was easily met. But the then industry minister Ian Macfarlane described the task as an “enormous challege”, and industry figures suggested the required wind energy was “almost impossible”. Even Taylor initially said the target was “too high”.

The cut itself was bad enough for the renewable energy industry. But the uncertainty created during the review devastated investment.

Renewable energy investment in Australia. There was a drop in investment during the review of the target, and a significant uptick once the bipartisan ship and a new target was restored. [Available from: https://www.abc.net.au/news/2018-01-18/renewable-energy-investment-in-australia/9339350%5D
BNEF

Investment did boom following bipartisan support for the new, lower target. But we can only speculate what may have been possible without the uncertainty created by the review.

It’s not looking rosy for renewables

The drop-off in investment is a worrying trend for the renewable energy industry, and for climate action more broadly. We can expect a drop-off in new additions in capacity in line with the drop in investment.

Australian Energy Market Commission data showing committed renewable energy projects for the next 12-18 months.

The table above shows the current committed projects for next 12-18 months. While more projects are likely to be committed over the next 18 months, it’s hard to see the peak of 2018 repeated soon, particularly with investment dropping away.

The achievement of the renewable energy target leaves a federal policy void. Renewable energy may now be the lowest-cost source of new electricity supply. But it is competing against assets such as coal-fired power stations with sunk costs – meaning that new renewables projects are essentially competing only with a coal plant’s fuel costs. Absent a price on carbon or similar policy, coal assets are allowed to pollute the atmosphere for free.

The renewable energy target has helped displace fossil fuel-derived power from the electricity mix.
AAP



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What next?

There are lessons to be learned from Germany to ensure a less bumpy transition to a decarbonised electricity sector. “Deployment corridors” help make the development of renewable energy sources more predictable, improve integration into the power system, and keep additional costs to consumers manageable.

But unless emissions-intensive generation closes or renewable energy support is reintroduced, renewable energy expansion in Australia is unlikely to proceed at the pace required to meet the Paris targets. Keeping the global average temperature rise well below 2℃ requires “rapid and profound near-term decarbonisation of energy supply” and strong upscaling of renewables.

The states are attempting to fill the federal policy gap. Several have their own renewable energy support schemes and all states in the east coast’s National Electricity Market have committed to net zero emissions by 2050.

A coal station in Victoria’s Latrobe Valley.
Julian Smith/AAP

Continued renewables growth also requires transmission infrastructure and storage technologies to ensure the distributed energy can be delivered where it is needed, and that reliability is maintained. Several states have also recently committed resources to transmission investment.




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The state-led action calls into question the effectiveness of the Council of Australian Governments’ (COAG) energy council. The group comprises the nation’s energy ministers and claims to maintain national “policy leadership” on energy. However it hasn’t met in almost nine months and its overarching agreement is more then 15 years old, and doesn’t refer to environmental outcomes or emissions cuts.

A new direction for the council is probably wishful thinking in the current political environment. But as emissions continue to rise in Australia, the need for significant reform only intensifies.The Conversation

Dylan McConnell, Researcher at the Australian German Climate and Energy College, University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The air above Antarctica is suddenly getting warmer – here’s what it means for Australia



Antarctic winds have a huge effect on weather in other places.
NASA Goddard Space Flight Center/Flickr, CC BY-SA

Harry Hendon, Australian Bureau of Meteorology; Andrew B. Watkins, Australian Bureau of Meteorology; Eun-Pa Lim, Australian Bureau of Meteorology, and Griffith Young, Australian Bureau of Meteorology

Record warm temperatures above Antarctica over the coming weeks are likely to bring above-average spring temperatures and below-average rainfall across large parts of New South Wales and southern Queensland.

The warming began in the last week of August, when temperatures in the stratosphere high above the South Pole began rapidly heating in a phenomenon called “sudden stratospheric warming”.




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In the coming weeks the warming is forecast to intensify, and its effects will extend downward to Earth’s surface, affecting much of eastern Australia over the coming months.

The Bureau of Meteorology is predicting the strongest Antarctic warming on record, likely to exceed the previous record of September 2002.

(Left) Observation of September 2002 stratospheric warming compared to (right) 2019 forecast for September.
The forecast for 2019 was provided by the Australian Bureau of Meteorology and was initialised on August 30, 2019.

What’s going on?

Every winter, westerly winds – often up to 200km per hour – develop in the stratosphere high above the South Pole and circle the polar region. The winds develop as a result of the difference in temperature over the pole (where there is no sunlight) and the Southern Ocean (where the sun still shines).

As the sun shifts southward during spring, the polar region starts to warm. This warming causes the stratospheric vortex and associated westerly winds to gradually weaken over the period of a few months.

However, in some years this breakdown can happen faster than usual. Waves of air from the lower atmosphere (from large weather systems or flow over mountains) warm the stratosphere above the South Pole, and weaken or “mix” the high-speed westerly winds.

Very rarely, if the waves are strong enough they can rapidly break down the polar vortex, actually reversing the direction of the winds so they become easterly. This is the technical definition of “sudden stratospheric warming.”

Although we have seen plenty of weak or moderate variations in the polar vortex over the past 60 years, the only other true sudden stratospheric warming event in the Southern Hemisphere was in September 2002.

In contrast, their northern counterpart occurs every other year or so during late winter of the Northern Hemisphere because of stronger and more variable tropospheric wave activity.

What can Australia expect?

Impacts from this stratospheric warming are likely to reach Earth’s surface in the next month and possibly extend through to January.

Apart from warming the Antarctic region, the most notable effect will be a shift of the Southern Ocean westerly winds towards the Equator.

For regions directly in the path of the strongest westerlies, which includes western Tasmania, New Zealand’s South Island, and Patagonia in South America, this generally results in more storminess and rainfall, and colder temperatures.

But for subtropical Australia, which largely sits north of the main belt of westerlies, the shift results in reduced rainfall, clearer skies, and warmer temperatures.

Past stratospheric warming events and associated wind changes have had their strongest effects in NSW and southern Queensland, where springtime temperatures increased, rainfall decreased and heatwaves and fire risk rose.

The influence of the stratospheric warming has been captured by the Bureau’s climate outlooks, along with the influence of other major climate drivers such as the current positive Indian Ocean Dipole, leading to a hot and dry outlook for spring.

Anomalous Australian climate conditions during the nine most significant polar vortex weakening years (1979, 1988, 2000, 2002, 2004, 2005, 2012, 2013, 2016) on both maximum and minimum temperatures, and rainfall for October-November, as compared to all other years between 1979-2016.
Bureau of Meteorology

Effects on the ozone hole and Antarctic sea ice

One positive note of sudden stratospheric warming is the reduction – or even absence altogether – of the spring Antarctic ozone hole. This is for two reasons.

First, the rapid rise of temperatures in the upper atmosphere means the super cold polar stratospheric ice clouds, which are vital for the chemical process that destroys ozone, may not even form.

Secondly, the disrupted winds carry more ozone-rich air from the tropics to the polar region, helping repair the ozone hole.

We also expect an enhanced decline in Antarctic sea ice between October and January, particularly in the eastern Ross Sea and western Amundsen Sea, as more warm water moves towards the poles due to the weaker westerly winds.




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Thanks to improvements in modelling and the Bureau’s new supercomputer, these types of events can be forecast better than ever before. Compared to 2002, when we didn’t know much about the event until after it had happened, this time we’ve had almost three weeks’ notice that a very strong warming event was coming. We also know much more about the process that has been set in train, that will affect our weather over the next one to four months.The Conversation

Harry Hendon, Senior Principal Research Scientist, Australian Bureau of Meteorology; Andrew B. Watkins, Manager of Long-range Forecast Services, Australian Bureau of Meteorology; Eun-Pa Lim, Senior research scientist, Australian Bureau of Meteorology, and Griffith Young, Senior IT Officer, Australian Bureau of Meteorology

This article is republished from The Conversation under a Creative Commons license. Read the original article.